The Nature of Monsters BY Clare Clark. Harcourt. Hardcover, 400 pages. $25.

The cover of The Nature of Monsters

That Clare Clark is the author of a critically acclaimed first novel titled The Great Stink should make perfect sense to readers of her second offering. Set largely in the malodorous backstreets and poorly ventilated chambers of early-eighteenth-century London, The Nature of Monsters, like its predecessor (which explores the city's sewers a century later), is a distinctly pungent reading experience—one in which the "powerful stink of pig shit and rotting refuse" mingles with foul-smelling tisanes, decomposing elixirs, and canals choked with "dung and dead cats" to form an olfactory edifice so impressive it easily displaces the frequently evoked dome of Saint Paul's Cathedral as the symbolic heart of the novel.

Such an atmosphere is fitting, because Clark's narrator, Eliza Tally, is both literally and figuratively up to her ankles in muck. Forced to serve as a maid in a house where opium-amplified insanity presides, a very pregnant Eliza spends her days battling sticky London soot, fetching water, scrubbing floors, and wondering why her employer, an apothecary who smells of "stale wine and liquorice and something charred and foreign like burnt caramel," wears a veil when he goes out. If the view of Saint Paul's from her attic bedroom occasionally draws her eyes skyward, the clomping of the apothecary's boots on the floor below, the heavy odor of her airless room, and the threat of beatings and imprisonment in the icy kitchen or coal cellar oblige Eliza to focus on the increasingly sinister here and now.

Though Clark evokes Eliza's surroundings and predicament with authority, she is less assured when it comes to setting her mechanism in motion. The problem is not one of concept—Eliza's torments at the hands of the apothecary, who hopes to use her and her offspring as evidence in a sordid experiment on the causes of birth defects, are both fascinating and frightening—but of implementa­tion. Eliza's first-person narration is interspersed with notes and letters, for the most part either written by the apothecary or sent to him. These unexplained textual disruptions, which allow us to comprehend the nature and degree of the apothecary's madness (he imagines, for instance, an exhibition display of "skeleton of monkey . . . alongside that of human infant idiot in cage to underline simian association"), combine with Eliza's rather overgenerous use of portentous detail to telegraph the multiple twists and turns built into the novel. Yet if Clark falters a little this time around, the pleasures here are many, and one hopes this latest excursion into the underside of historic London won't be her last.